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NebraskaSC Severe Weather Photography Videography ADMIN January 17, 2019
Updated January 18, 2019

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We are looking for pictures from your camera, cell phone, tablet or any other photographic device.

This group is about 3 different types of cloud groups, all rare indeed, never one the same. Shelf Clouds / Arcus Clouds / Roll Clouds

Images are in Que

Group Description

What is ...
A Shelf Clouds and or Arcus Clouds are defined as a low, horizontal cloud formation associated with the leading edge of thunderstorm outflow, or occasionally with a cold front even in the absence of thunderstorms. Roll clouds and shelf clouds are the two types of arcus clouds, slight variations in their generation and appearance being the difference.

How They Form
Cool, sinking air from a storm cloud's downdraft spreads out across the surface with the leading edge called a gust front. This outflow undercuts warm air being drawn into the storm's updraft. As the cool air lifts the warm moist air, water condenses creating a cloud which often rolls with the different winds above and below (wind shear).

What is a Roll Cloud
A roll cloud is a low, horizontal, tube-shaped, and relatively rare type of arcus cloud. They differ from shelf clouds by being completely detached from the thunderstorm base or other cloud features. Roll clouds usually appear to be "rolling" about a horizontal axis. They can be a sign of possible microburst activity.

What is a Shelf Cloud
A shelf cloud is a low, horizontal wedge-shaped arcus cloud. Unlike a roll cloud, a shelf cloud is attached to the base of the parent cloud (usually a thunderstorm). Rising cloud motion often can be seen in the leading (outer) part of the shelf cloud, while the underside often appears turbulent and wind-torn.

Occasionally people seeing a shelf cloud may believe they have seen a wall cloud. This is a common mistake, since an approaching shelf cloud appears to form a wall made of cloud. Generally speaking, a shelf cloud appears on the leading edge of a storm, and a wall cloud will usually be at the rear of the storm.

Additional Info

  • This group doesn't care how many other groups a photo is in
  • Accepted content types: Photos, Videos, Images, Art, Screenshots
  • Accepted safety levels: Safe
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